The
most common reason evaps perforate is that moisture causes the system to
corrode from the outside in. The corrosion occurs because as warm (ambient)
air is passed over the cooled coils, the moisture in the air will condense
onto the coils. And often, people will run their AC until their destination,
thus leaving the coils wet. When dirty air is passed over wet coils, the
dirt will adhere to the coils, making it even more difficult for the water
on the coils to evaporate. Thus filtering the air of this dirt will help
to lengthen the life of the evap. And this is why EVERYONE in the know,
recommends running the HVAC fan with the AC off for the last mile or so
of each trip in order to dry the evap off.

Thanks to Jon (obviously a very brave man)
for this comment,which is definitely not "hot air"...

Just
had to tell someone that I replaced my own evap core last week. Took
about 20manhours
for a very experienced shade tree mechanic. Mostly just had to take
time tobag
up and label all parts (screws & fasteners) as well as writing down
each step and howlong
it took. This was the most difficult repair I have ever done - and
I have rebuilt enginesbefore!
However the air is now ice cold, though it has only been a week...

BTW,
I bought the parts from Swedish Engineering. Great guys, they give
good adviceand
even faxed me the instructions for the repair out of their copy of the
official Volvoservice
manual. Also, their price was fantastic, about $320 for the complete
evap kit.

So,
unless you consider yourself an expert home mechanic, I agree with everyone'sassessment,
let the pros handle this one. But if you are bold - well I wish you
muchsuccess
and very cold air!